Locking device for foot levers



July 17, 1934. c. HOWARD LOCKING DEVICE FOR FOOT LEVERS Filed March 25, 1953 Patented July 17, 1934 VII'JOCKINGV DEVICE FOR FOOT lvanfo. Howard,,Mario,n, Ohio, assignor to r'he Marion steam Shovel Company, Marion, Ohio,

a corporation of Ohio Application March 23, 1933, Serial No. 662,298.

' 7 Claims; 0114-540) This invention relates to operating mechanism for brakes and similar'devices and more particularly to a locking device for a foot lever forming a part of such an operating mechanism. It is customary to provide the operating member or. foot lever ofs'uch. a mechanism with a locking device which will'retain it in its operative position, that is, in a position to maintain the brake set. However, the means which have been provided for actuating the locking device to release the foot lever haven'ot been satisfactory. They were not only of such a character that they were inconvenientand diificult to operate but often" the operator was required to so change his posi- "tion in order to' releasejthe lock that he would lose control of the foot lever and the brakefwith which it is connected. In many cases it is imI-: portant that the operator should retain control of the brake so as to release the same gradually.- '5F0r example, if the brake on the" hoistingdruni of an excavating machine is "suddenly released the load'supported thereby will be permitted to drop. V

One object of the invention is'to provide a 21 i locking device fora foot. lever'or the like o'fsuch' a character that the operatormay release the same without losing control rthe foot lever} A further object of the invention is to provide. such a locking device with releasing means which may be moved to an operative position but which will not immediately release the footlever A further object of the invention is to; provide. such a locking device with spring actuating means which when in one position will tend to ;move the locking device toward its locking position, and when inanother position will tend to retract the locking'device and thus disengage the same from the foot lever. l e

- A further object of the invention is to provide 0such a locking device with releasing means including a spring actuated part whicli is movable into and out of a position to" retract the locking device and which is provided with means where by it maybe quickly and easilyoperated by the operator without substantially changing his position.

A further object oithe inventionis to provide an operating mechanism comprising such" a lock ing device whichwillbe'simple in its" construction ;.and operation and which may be low cost.

Other objects ofthe invention will appear as the-'smecha'nism is described in detail:

I In the accompanying drawing Fig; is-a side i 5 elevation of an operating mechanism embeaying produced at- 9.

my invention Showing these-me in its locked position; Fig. 2 is a plan view of 'the operating mechanism, as shown in Fig. 1'; Fig. 3 is a side elevation of the operating mechanism showing the y same in its released position and Fig; 1' is adetail view of the locking pawl. and its controlling arms. r I g In this drawing 1 have illustrated one embodiment of my invention and have shown the same asapplied to a band brake but will be under- 66- stood that this particular embodiment has beenchosen for the purpose of -il1ust ration only and; that the locking device may-takevarious rams and; may be-appliedto operating mechanisms for controlling devices of various kinds.

The particular mechanism here illustrated is designed primarily 'for use in connection witlia: brake on one of the cable drums-of an excavatingmachine. A part of the floor structure or foot I board of such an excavating machine isshown at 75' 5 and the brake comprisesa drum 6 and-a brake band 7-which' extends about-the drumandhas one end anchored, "as sl'iowii'at 8-, and has its other end connected with on'e arm of a; bell, crank '9', as shown at 10. The other armof the bell crank is 8i? pivotal-1y connecte'dgto'f of link 11" which in turn is pivotally connected at l2to a lever 13 which is mounted on the floor structure 5". The link 1 1 andlever 1-3 con'stitutea toggle which when moved to itsextended or straight position; will? cause the brake to beset and which'when broken will release the brake, A crank arm l4 is ri'gidly' con-- nected with the lever l 3 'and has attached thereto one end of aconnectin'g rod 15, the other end' of which is connected with the operating mechanism. 96 It will be understoodthat the particular; brake mechanism here illustrated is merely illustrative andthat the brake or other device to'be operated may take various forms. v The mechanism for operating the brake corn-' prises afoot" lever I6 which, in the present in-" st'anca'is L-shaped and comprises a substantially horizontal portion mounted at one end on a short shaft 1'7 which isfsu'pported" by a bracket 1-8 carriedby the floor structure.- At that end 160 remote from its axisthe lever comprises anupe wardly extending part 19"which'proje'cts through" a slot**20 in the foot board" and isprovided at itsupper end with a-foot piece or pedal 21, which-is here shownas pivota lly jmounted on the lever. Rigidly connected with the pivoted end of the l'e'ver isa crankarm 22 to whichis a't taclied the adjacent end of the'connect'i'ng rod 15; A- spring- 23' is connected at one w end with bracket- 24 dependin'g from the fi'oor structureand' 110 at its other end with a rod 25 which is secured to the crank arm 22 and tends to move the foot lever 16 upwardly to its inoperative position. The upwardly extending part 19 of the foot lever is provided with a plurality of locking teeth which are preferably in the form of ratchet teeth, as shown at 26. Cooperating with these locking teeth is a locking device which is preferably in the form of a pawl 27 carried by a short shaft 28 mounted in brackets 29 on the floor structure. The pawl is yieldably pressed toward its locking position and when the foot lever is depressed the pawl will engage one of the locking teeth and thus retain the lever in its depressed position. It will be apparent that the downward movement of the lever will move the crank arm 22 and lever 13 in such directions as to straighten the toggle 1l13 and thus set the brake.

Suitable means are provided for actuating the pawl and for properly controlling its movements. In the present construction I have connected with the pawl a controlling device which comprises two arms 30 and 31, rigidly connected with the pawl and projecting on opposite sides of the axis thereof. As here shown, these arms are formed from a single plate which is mounted on the shaft 28 which carries the pawl and which may, if desired, be rigidly secured to the hub of the pawl. One edge of this plate is continuous between the outer ends of the two arms and constitutes a contact surface adapted to be engaged by an actuating device. In the present instance, this contact surface is a straight flat surface and faces downwardly. When the arm 30 is subjected to upward pressure the pawl will be moved toward its locking position and when the arm 31 is subjected to upward pressure it will tend to retract the pawl or move the same out of engagement with-the locking tooth on the foot lever and thus constitutes one member of a releasing device. Preferably a single device is provided for exerting pressure on both arms, this device being of such a character that it can be moved into and out of operative engage ment with the respective arms. In the construction here shown, this actuating device comprises an arm 32 pivotally mounted beneath the floor structure on a short shaft 33. Slidably mounted on this arm 32 for longitudinal movement is a plunger 34 which is acted upon by a spring 35 which tends to move the same outwardly. The spring pressed member or plunger 34- is held by its spring in constant engagement with the contact surface of a controlling device or arms 30 and 31 and when the actuating device is moved about its axis this spring pressed member slides along the contact surface across the axis of the arms, so that the pressure is transferred from one arm to the other. When the actuating device is in engagement with either arm it is so inclined with relation thereto that the action of the plunger on the arm will tend to hold the actuating device in the position to which it has been moved until positive force has been applied thereto. Any suitable means may be provided for shifting the actuating device from one position to the other but I prefer to connect with the actuating device an operating lever 36, the free end of which extends upwardly through the slot 20 in the foot board and has at its upper end a laterally extending part or lip 37 which may be engaged by the foot of the operator to either elevate or depress the lever 36. The

downward movement of the operating lever 36. is limited by a lug 38 which engages the foot board at the end of the slot 20. The upward movement of the lever is limited by a stop 39 which is preferably in the form of a screw mounted in the lever and arranged to engage the foot board at one side of the slot 20. When the operating lever 36 is in its depressed position the actuating device will be in engagement with the controlling arm 30 and the spring pressed member will move the pawl toward its locking position. When the lever is elevated the spring pressed member will be moved along the con tact surface into engagement with the releasing arm 31 and will exert an upward pressure thereon. However, when the foot lever is in its locked position the pull exerted thereon by the brake mechanism and by the spring 23 ofiers a very substantial resistance to the movement of the pawl out of engagement with the locking tooth, and the spring 35 which actuates the plunger 34 is made of a strength which is insufficient to overcome this resistance. Consequently the movement of the actuating device into engagement with the arm 31 will not of itself actuate the pawl to release the foot lever but the lever will remain locked until the operator depresses the same slightly and thereby decreases the resistance offered to the retraction of the pawl to such an extent that the spring can impart movement to the pawl. The action or" the spring pressed member then moves the pawl from the position shovm in Fig. 1 to the position shown in Fig. 3 and the foot lever is moved upwardly under the action of the spring 23, its movement being limited by a stop screw 40 mounted thereon. By adjusting the stop 39 the point at which the spring pressed member will act on the arm 31 will be spaced different distances from the axis of the arm, thus, due to the varying leverage, exerting a greater or lesser force on the pawl, and accommodating the device to different operating conditions or different loads without changing the spring. It will be apparent th refore that at the time the locking device is retracted the operator has his foot on the foot lever and is applying pressure thereto so that the lever and the brake mechanism are under cor. plete control.

In the organization shown it is desirable to provide some means for limiting the movement of the pivoted arms 30 and 31 by the spring actuated plunger, otherwise when the parts are in the position shown in Fig. 3 the plunger would continue to move the pawl unit, after the pawl had been disengaged from the rack, until the arm 31 moved out of engagement with the plunger. Likewise with the parts in the position shown in Fig. 3, when the lever 36 is depressed to move the spring pressed plunger into engagement with the arm 30, prior to the setting of the brake, the plunger would continue to move this arm until the arm had moved out of engagement with the plunger. The movement of the arms to these extreme positions is undesirable and might seriously interfere,

with the operation of the device. Any suitable means may be provided for limiting the movement of the pawl unit and, in the present construction, I have rigidly connected with the arms 30 and 31 two fingers 41 and 42 which, in the present instance, are rigidly secured to the hub of the pawl and extend in opposite directions therefrom. These fingers constitute stops adapted to engage the floor board and they are so arranged as to positively check the movement of the pawl unit after the pawl has been moved to the desired position. 1

its

While I have shown and described one embodiment of my invention I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In an operating mechanism of the character described, comprising an operating member having means for connecting the same with a part to be operated, and a device to engage said operating member and lock the same in its operative position, a pivoted device operatively connected with said locking device and having two parts arranged on opposite sides of its axis and connected one to the other by a continuous contact surface, an actuating device comprising a spring pressed member having sliding engagement with said contact surface, means for moving said spring pressed member from one side of the axis of said pivoted device to the other side of said axis, and adjustable means to limit the movement of said spring pressed member by the last mentioned means. 7

' 2. In an operating mechanism of the character described, comprising an operating member having means for connecting the same with a part to be operated and having a series of locking teeth, and a pawl movable into engagement with one of said teeth to lock said member in its operative position, an arm rigidly connected with said pawl for movement therewith, an actuating device movable into and out of operative. relation to said arm and comprising a plunger and a spring to press said plunger against said arm when it is located adjacent thereto, means for moving said actuating device from one position to the other,

and adjustable means for causing said plunger to engage said arm at different distances from the axis thereof.

3. In a mechanism of the character descr bed,

a supporting structure, a foot lever pivotally mounted beneath said supporting structure, having means to connect the same with a part to be operated and having a part extending above said structure, said part of said lever having a plurality of locking teeth, a pawl mounted on said structure and arranged to engage one of said teeth and lock said lever in its depressed position, a pivoted member connected with said pawl and having a downwardly facing contact surface extending across its axis, an actuating device pivotally mounted beneath said structure and comprising a spring pressed member having sliding engagement with said contact surface, and a lever connected with said actuating device and extending above said supporting structure.

4. In a mechanism of the character described, a supporting structure, a foot lever pivotally mounted beneath said supporting structure, having means to connect the same with a part to be operated and having a part extending above said structure, said part of said lever having. a plurality of locking teeth, a pawl mounted on said structure and arranged to engage one of said teeth and lock said lever in its depressed position, a pivoted member connected with said pawl and having a downwardly facing contact surface extending across its axis, an actuating device pivotally mounted beneath said structure and comprising a spring pressed member having sliding engagement with said contact surface, a lever connected with said actuating device and extending above said supporting structure, and a stop adjustably mounted on the last mentioned lever and arranged to engage a part of said supporting structure.

5. In a mechanism of the character described, a supporting structure, a foot lever pivotally mounted beneath said supporting structure, having means to connect the same with a part to be operated and having a part extending above said structure, said part of said lever having a plurality of locking teeth, a pawl mounted on said structure and arranged to engage one of said teeth and lock said lever in its depressed position, a pivoted member connected with said pawl and having a downwardly facing contact surface extending across its axis, an actuating device pivotally mounted beneath said structure and comprising a spring pressed member having sliding engagement with said contact surface, a lever connected with said actuating device and extending above said supporting structure, and stops connected with said pivoted member and arranged to engage said supporting structure on opposite sides of the axis of said pivoted member to limit the movement of the latter by said spring pressed member.

6. In a mechanism of the character described comprising a floorstructure, an operating member extending through said structure and having means below said structure for'connecting the same with a part to be operated and having means above said structure for actuating the same, and a device to engage said operating member and lock the same in its operating position, a releasing member connected with said locking device, a spring pressed member movable independently of said releasing member into and out of a position in which it will act on said releasing member in a direction to retract said locking device, and

meansincluding an operating part arranged above said floor structure for moving said spring pressed member into said position.

7. In a mechanism of the character described, a supporting structure, 7 a foot lever pivotally mounted beneath said supporting structure, having means to connect the same with a part to be operated and having a part extending above said structure, said lever having a plurality of locking teeth, a pawl mounted on said structure and arranged to engage one of said teeth and lock said lever in its depressed position, a pivoted device operatively connected with said pawl and having arms extending in opposite directions from its axis, an actuating device movably mounted beneath said structure and having a part movable into operative engagement with either of said arms, and means having an operating part arranged above said supporting structure to move said actuating device from one position to the other.

IVAN C. HOWARD. 

